Facile synthesis of porous Cu-Sn alloy electrode with prior selectivity of formate in a wide potential range for CO2 electrochemical reduction

CO2 electroreduction is regarded as a potential way to mitigate CO2 level and produce value-added chemicals. Although Cu-Sn bimetallic electrodes show an excellent selectivity towards targeted formate or CO, the better performance is only achieved in a narrow potential range. Herein, porous Cu6.26Sn5 electrode is prepared. Alloying Cu with Sn atoms tunes the electronic structure of catalyst, which balances the adsorption and protonation of CO2*– intermediate. The unique rice spike-like microstructure intensifies the local electric field to raise the CO2 concentration at the reaction sites. As a result, it exhibits a superior selectivity towards formate with the maximum faradaic efficiency (FEformate) of 97.8 ± 2.4 %. The better selectivity (FEformate over 80 %) is maintained over a wider potential range of 600 mV, which outperforms the majority of reported Cu-Sn bimetallic electrodes. This research provides a promising way to concurrently regulate morphological and electronic structure of alloy electrodes for efficient CO2 electroreduction.